Touch panel and display device using the same

ABSTRACT

A touch panel includes a substrate, a transparent conductive layer and a plurality of electrodes. The substrate has a first surface and a second surface opposite to the first surface. The transparent conductive layer is formed on the first surface of the substrate. The transparent conductive layer includes a plurality of separated carbon nanotube structures. The electrodes are electrically connected to the transparent conductive layer. Each electrode is connected with the end of at least one of the carbon nanotube structures such that each carbon nanotube structure is in contact with at least two opposite electrodes. Further, a display device using the above-described touch panel is also included.

RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application No. 200710305830.5, filed on 2007, Dec. 27 inthe China Intellectual Property Office, the disclosure of which isincorporated herein by reference. This application is related tocommonly-assigned co-pending applications entitled, “TOUCH PANEL”, Ser.No. 12/286,266, filed on Sep. 29, 2008; “TOUCH PANEL”, Ser. No.12/286,141, filed on Sep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICEUSING THE SAME”, Ser. No. 12/286,189, filed on Sep. 29, 2008; “TOUCHPANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,181, filed onSep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No.12/286,176 filed on Sep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICE USINGTHE SAME”, Ser. No. 12/286,166, filed on Sep. 29, 2008; “TOUCH PANEL ANDDISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,178, filed on Sep. 29,2008; “TOUCH PANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No.12/286,148, filed on Sep. 29, 2008; “TOUCHABLE CONTROL DEVICE”, Ser. No.12/286,140, filed on Sep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICEUSING THE SAME”, Ser. No. 12/286,154, filed on Sep. 29, 2008; “TOUCHPANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,216, filed onSep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No.12/286,152, filed on Sep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICEUSING THE SAME”, Ser. No. 12/286,145, filed on Sep. 29, 2008; “TOUCHPANEL, METHOD FOR MAKING THE SAME, AND DISPLAY DEVICE ADOPTING THESAME”, Ser. No. 12/286,155, filed on Sep. 29, 2008; “TOUCH PANEL ANDDISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,179, filed on Sep. 29,2008; “TOUCH PANEL, METHOD FOR MAKING THE SAME, AND DISPLAY DEVICEADOPTING THE SAME”, Ser. No. 12/286,228, filed on Sep. 29, 2008; “TOUCHPANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,153, filed onSep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No.12/286,184, filed on Sep. 29, 2008; “METHOD FOR MAKING TOUCH PANEL”,Ser. No. 12/286,175, filed on Sep. 29, 2008; “METHOD FOR MAKING TOUCHPANEL”, Ser. No. 12/286,195, filed on Sep. 29, 2008; “TOUCH PANEL ANDDISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,160, filed on Sep. 29,2008; “TOUCH PANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No.12/286,220, filed on Sep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICEUSING THE SAME”, Ser. No. 12/286,227, filed on Sep. 29, 2008; “TOUCHPANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,144, filed onSep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No.12/286,218, filed on Sep. 29, 2008; “TOUCH PANEL AND DISPLAY DEVICEUSING THE SAME”, Ser. No. 12/286,142, filed on Sep. 29, 2008; “TOUCHPANEL AND DISPLAY DEVICE USING THE SAME”, Ser. No. 12/286,146, filed onSep. 29, 2008; “TOUCH PANEL, METHOD FOR MAKING THE SAME, AND DISPLAYDEVICE ADOPTING THE SAME”, Ser. No. 12/286,151, filed on Sep. 29, 2008;“ELECTRONIC ELEMENT HAVING CARBON NANOTUBES”, Ser. No. 12/286,143, filedon Sep. 29, 2008; and “TOUCH PANEL, METHOD FOR MAKING THE SAME, ANDDISPLAY DEVICE ADOPTING THE SAME”, Ser. No. 12/286,219, filed on Sep.29, 2008. The disclosures of the above-identified applications areincorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to a carbon-nanotube-based touch panel anda display device using the same.

2. Discussion of Related Art

Following the advancement in recent years of various electronicapparatuses, such as mobile phones, car navigation systems and the like,toward high performance and diversification, there has been continuousgrowth in the number of electronic apparatuses equipped with opticallytransparent touch panels at the front of their respective displaydevices (e.g., a display such as a liquid crystal panel). A user of anysuch electronic apparatus operates it by pressing or touching the touchpanel with a finger, a pen, a stylus, or a like tool while visuallyobserving the display device through the touch panel. A demand thusexists for such touch panels that are superior in visibility andreliable in operation.

At present, different types of touch panels, including resistance,capacitance, infrared, and surface sound-wave types, have beendeveloped. The capacitance-type touch panel has several advantages suchas high accuracy and excellent transparency, and thus has been widelyused.

A conventional capacitance-type touch panel includes a glass substrate,a transparent conductive layer, and four electrodes. The material of thetransparent conductive layer is, typically, selected from a groupconsisting of indium tin oxide (ITO) and antimony tin oxide (ATO). Theelectrodes are made of metal and separately formed on a surface of thetransparent conductive layer. Further, a protective layer is formed onthe surface of the transparent conductive layer that faces away from thesubstrate. The material of the protective layer has insulative andtransparent characteristics.

In operation, an upper surface of the touch panel is pressed/touchedwith a touch tool, such as a user's finger or an electrical pen/stylus.Visual observation of a screen on the liquid crystal display deviceprovided on a backside of the touch panel is possible. In use, becauseof an electrical field of the user, a coupling capacitance forms betweenthe user and the transparent conductive layer. For high frequencyelectrical current, the coupled capacitance is a conductor, and thus thetouch tool takes away a little current from the touch point. Currentflowing through the four electrodes cooperatively replaces the currentlost at the touch point. The quantity of current supplied by the fourelectrodes is directly proportional to the distances from the touchpoint to the electrodes. A touch panel controller is used to calculatethe proportion of the four supplied currents, thereby detectingcoordinates of the touch point on the touch panel.

The optically transparent conductive layer (e.g., ITO layer) isgenerally formed by means of ion-beam sputtering, and this method isrelatively complicated. Furthermore, the ITO layer has generally poormechanical durability, low chemical endurance, and uneven resistanceover an entire area of the touch panel. Additionally, the ITO layer hasrelatively low transparency. All the above-mentioned problems of the ITOlayer tend to yield a touch panel with somewhat low sensitivity,accuracy, and brightness.

What is needed, therefore, is to provide a durable touch panel with highsensitivity, accuracy, and brightness, and a display device using thesame.

SUMMARY

A touch panel includes a substrate, a transparent conductive layer and aplurality of electrodes. The substrate has a first surface and a secondsurface opposite to the first surface. The transparent conductive layeris formed on the first surface of the substrate. The transparentconductive layer includes a plurality of separated carbon nanotubestructures. The electrodes are electrically connected to the transparentconductive layer. Each electrode is connected with the end of at leastone of the carbon nanotube structures such that each carbon nanotubestructure is in contact with at least two opposite electrodes. Further,a display device using the above-described touch panel is also included.

Other advantages and novel features of the present touch panel anddisplay device using the same will become more apparent from thefollowing detailed description of the present embodiments, when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present touch panel and display device using thesame can be better understood with reference to the following drawings.The components in the drawings are not necessarily to scale, theemphasis instead being placed upon clearly illustrating the principlesof the present touch panel and display device using the same.

FIG. 1 is a schematic view of a partially assembled touch panel, inaccordance with a present embodiment.

FIG. 2 is a cross-sectional schematic view of the touch panel of thepresent embodiment, taken along a line II-II of FIG. 1.

FIG. 3 is a schematic view of a transparent conductive layer used in thetouch panel of FIG. 1.

FIG. 4 shows a Scanning Electron Microscope (SEM) image of a carbonnanotube film.

FIG. 5 is a structural schematic of a carbon nanotube segment.

FIG. 6 is essentially a schematic cross-sectional view of the touchpanel of the present embodiment used with a display element of a displaydevice, showing operation of the touch panel with a touch tool.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate at least one embodiment of the present touch panel anddisplay device using the same, in at least one form, and suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made to the drawings to describe, in detail,embodiments of the present touch panel and display device using thesame.

Referring to FIGS. 1, 2 and 3, a touch panel 20 includes a substrate 22,a transparent conductive layer 24, a transparent protective layer 26,and a plurality of electrodes 28. The substrate 22 has a first surface221 and a second surface 222 at opposite sides thereof respectively. Thetransparent conductive layer 24 is disposed on the first surface 221.The transparent conductive layer 24 includes a plurality of spacedcarbon nanotube structures 240.

The ends of each carbon nanotube structures 240 are electricallyconnected to opposite electrodes 28, and each of electrodes 28 areconnected to at least one carbon nanotube structures 240. The carbonnanotube structures 240 and the electrodes 28 form an equipotentialsurface on the transparent conductive layer 24. The transparentprotective layer 26 covers the electrodes 28, and the exposed surface ofthe transparent conductive layer 24. In the present embodiment, each ofelectrodes 28 is connected to each of the carbon nanotube structures240.

The substrate 22 has a planar structure or a curved structure. Thematerial of the substrate 22 can be selected from the group consistingof glass, quartz, diamond, and plastics. The substrate 22 is made from atransparent material, e.g., either flexible or stiff, depending onwhether a flexible device is desired or not. The substrate 22 is used tosupport the transparent conductive layer 24.

The transparent conductive layer 24 includes a plurality of separatedcarbon nanotube structures 240. The carbon nanotube structure can have astrip shape and a film structure (i.e., carbon nanotube strip-shapedfilm structure). The carbon nanotube structure can be a carbon nanotubefilm formed of a plurality of carbon nanotubes oriented along a samedirection (i.e., collinear and/or parallel). The carbon nanotubestructure also can be a plurality of stacked carbon nanotube films, andadjacent carbon nanotube films are combined by the van der Waalsattractive force therebetween. The carbon nanotube structure can also becomprised of a plurality of transparent carbon nanotube films locatedside by side. The films can also overlap with each other. The carbonnanotubes in the carbon nanotube film are arranged along a samedirection. The carbon nanotubes in adjacent carbon nanotube films arearranged along a same direction or different directions. In oneembodiment, a first plurality of carbon nanotube structures are parallelwith each other, and aligned along a first direction; and a secondplurality of carbon nanotube structures are parallel with each other,and aligned along a second direction. An angle between the firstdirection and the second direction is in a range from greater than orequal to 0° to less than or equal to 90°. In another embodiment (notshown), the first plurality of carbon nanotube structures are notparallel with each other, and the second plurality of carbon nanotubestructures are not parallel with each other too.

Referring to FIGS. 4 and 5, each carbon nanotube film comprises aplurality of successively oriented carbon nanotube segments 143 joinedend-to-end by van der Waals attractive force therebetween. Each carbonnanotube segment 143 includes a plurality of carbon nanotubes 145parallel to each other, and combined by van der Waals attractive forcetherebetween. The carbon nanotube segments 143 can vary in width,thickness, uniformity and shape. The carbon nanotubes 145 in the carbonnanotube film 143 are also oriented along a preferred orientation. Alength and a width of the carbon nanotube film can be arbitrarily set asdesired. A thickness of the carbon nanotube film approximately rangesfrom 0.5 nanometers to 100 micrometers. A distance between adjacentcarbon nanotube structures can be in an approximate range from 5nanometers to 1 millimeter. The carbon nanotubes 145 in the carbonnanotube structures 240 can be selected from a group consisting ofsingle-walled carbon nanotubes, double-walled carbon nanotubes, andmulti-walled carbon nanotubes. A diameter of each single-walled carbonnanotube is in an approximate range from 0.5 nanometers to 50nanometers. A diameter of each double-walled carbon nanotube is in anapproximate range from 1 nanometer to 50 nanometers. A diameter of eachmulti-walled carbon nanotube is in an approximate range from 1.5nanometers to 50 nanometers.

In the present embodiment, the transparent conductive layer 24 includesa plurality of separated carbon nanotube structures 240. A firstplurality of carbon nanotube structures are parallel with each other,and aligned along a first direction; and a second plurality of carbonnanotube structures are parallel with each other, and aligned along asecond direction. The first direction is perpendicular to the seconddirection.

A method for fabricating the above-described transparent conductivelayer 24 includes the steps of: (a) providing an array of carbonnanotubes, specifically, providing a super-aligned array of carbonnanotubes; (b) pulling out a carbon nanotube film or a carbon nanotubeyarn from the array of carbon nanotubes, by using a tool (e.g., adhesivetape, pliers, tweezers, or another tool allowing multiple carbonnanotubes to be gripped and pulled simultaneously); and if need be (c)preparing at least one above-described carbon nanotube film or carbonnanotube yarn to form a carbon nanotube structure, and placing aplurality of spaced above-described carbon nanotube structures on thesubstrate 22, thereby forming the transparent conductive layer 24.

In step (a), a given super-aligned array of carbon nanotubes can beformed by the substeps of: (a1) providing a substantially flat andsmooth substrate; (a2) forming a catalyst layer on the substrate; (a3)annealing the substrate with the catalyst layer in air at a temperaturein the approximate range from 700° C. to 900° C. for about 30 to 90minutes; (a4) heating the substrate with the catalyst layer to atemperature in the approximate range from 500° C. to 740° C. in afurnace with a protective gas therein; and (a5) supplying a carbonsource gas to the furnace for about 5 to 30 minutes and growing thesuper-aligned array of carbon nanotubes on the substrate.

In step (a1), the substrate can be a P-type silicon wafer, an N-typesilicon wafer, or a silicon wafer with a film of silicon dioxidethereon. In this embodiment, a 4-inch P-type silicon wafer is used asthe substrate.

In step (a2), the catalyst can be made of iron (Fe), cobalt (Co), nickel(Ni), or any alloy thereof.

In step (a4), the protective gas can be made up of at least one ofnitrogen (N2), ammonia (NH3), and a noble gas. In step (a5), the carbonsource gas can be a hydrocarbon gas, such as ethylene (C2H4), methane(CH4), acetylene (C2H2), ethane (C2H6), or any combination thereof.

The super-aligned array of carbon nanotubes can have a height of about50 microns to 5 millimeters and include a plurality of carbon nanotubesparallel to each other and approximately perpendicular to the substrate.The carbon nanotubes in the array of carbon nanotubes can be selectedfrom a group consisting of single-walled carbon nanotubes, double-walledcarbon nanotubes, and multi-walled carbon nanotubes. A diameter of eachsingle-walled carbon nanotube is in an approximate range from 0.5nanometers to 50 nanometers. A diameter of each double-walled carbonnanotube is in an approximate range from 1 nanometer to 50 nanometers. Adiameter of each multi-walled carbon nanotube is in an approximate rangefrom 1.5 nanometers to 50 nanometers.

The super-aligned array of carbon nanotubes formed under the aboveconditions is essentially free of impurities such as carbonaceous orresidual catalyst particles. The carbon nanotubes in the super-alignedarray are closely packed together by the van der Waals attractive force.

In step (b), the carbon nanotube film or yarn, can be formed by thesubsteps of: (b1) selecting one or more carbon nanotubes having apredetermined width from the array of carbon nanotubes; and (b2) pullingthe carbon nanotubes to form nanotube segments 143 at an even/uniformspeed to achieve a uniform carbon nanotube film or carbon nanotube yarn.

In step (b1), quite usefully, the carbon nanotube segment 143 includes aplurality of carbon nanotubes 145 parallel to each other. The carbonnanotube segments 143 can be selected by using an adhesive tape as thetool to contact the super-aligned array of carbon nanotubes. In step(b2), the pulling direction is substantially perpendicular to thegrowing direction of the super-aligned array of carbon nanotubes.

More specifically, during the pulling process, as the initial carbonnanotube segments are drawn out, other carbon nanotube segments are alsodrawn out end to end due to the van der Waals attractive force betweenends of adjacent segments. This process of drawing ensures a continuous,uniform carbon nanotube film or carbon nanotube yarn can be formed. Thepulling/drawing method is simple, fast, and suitable for industrialapplications. The detailed microstructure can be seen from FIG. 4.

In step (c), the carbon nanotube structure can be a carbon nanotube filmor a plurality of carbon nanotube films stacked with each other. Thecarbon nanotubes in adjacent two carbon nanotube films are arrangedalong a same direction or different directions. Distances betweenadjacent carbon nanotube structures approximately range from 5nanometers to 1 millimeter and can be adjusted according to the lightperformance property of the touch panel.

The carbon nanotube structure adhered to a surface of the substrate 22can be treated with an organic solvent. The carbon nanotube structurecan be treated by using organic solvent to soak the entire surface ofthe carbon nanotube structure. The organic solvent is volatilizable andcan, suitably, be selected from the group consisting of ethanol,methanol, acetone, dichloroethane, chloroform, and combinations thereof.In the present embodiment, the organic solvent is ethanol. After beingsoaked by the organic solvent, microscopically, carbon nanotube stringswill be formed by adjacent carbon nanotubes in the carbon nanotubestructure, that are able to do so, bundling together, due to the surfacetension of the organic solvent. In one aspect, part of the carbonnanotubes in the untreated carbon nanotube structure that are notadhered on the substrate will adhere on the substrate 22 after theorganic solvent treatment due to the surface tension of the organicsolvent. Then the contacting area of the carbon nanotube structure withthe substrate will increase, and thus, the carbon nanotube structure canfirmly adhere to the surface of the substrate 22. In another aspect, dueto the decrease of the specific surface area via bundling, themechanical strength and toughness of the carbon nanotube structure areincreased and the coefficient of friction of the carbon nanotubestructures is reduced. Macroscopically, the carbon nanotube structurewill be an approximately uniform film.

Distances between the carbon nanotube structures can be set according tothe optical transparent property of the touch panel. In the presentembodiment, distances between the carbon nanotube structures are in anapproximate range from 5 nanometers to 1 millimeter.

In step (c), the method for placing the carbon nanotube structures 240includes several process types. The first type includes the substeps of:separately and parallelly disposing a plurality of carbon nanotubestructures 240 along the first direction L1 on the first surface 221 ofthe substrate 22; separately and parallelly disposing another pluralityof carbon nanotube structures 240 along the second direction L2 on thefirst surface 221 of the substrate 22. An angle between the firstdirection L1 and the second direction L2 is in a range from greater than0° to less than or equal to 90°. The second type of process includes thesubsteps of disposing a plurality of carbon nanotube structures 240, sothat the carbon nanotube structures intersect each other to form anetwork.

The carbon nanotube structures 240 can be cut from a large size carbonnanotube film. In addition to being obtained from an array of carbonnanotubes, the large carbon nanotube film can also be obtained by othermethods.

Furthermore, since the optical refractive index and the opticaltransmission rate of the carbon nanotube structures and the gaps betweenthe carbon nanotube structures are different, a filling layer (notlabeled) having a similar optical refractive index and opticaltransmission rate as the carbon nanotube structure can be formed in thegap between the carbon nanotube structures.

It is to be noted that the shape of the substrate 22 and the transparentconductive layer 24 is chosen according to the requirements of the touchfield of the touch panel 20. Generally, the shape of the touch field maybe triangular or rectangular. In the present embodiment, the shapes ofthe touch field, the substrate 22, and the transparent conductive layer24 are all rectangular-shaped.

The electrodes are separately disposed. Two ends of each carbon nanotubestructure are electrically connected to two opposite electrodesrespectively, and each of electrodes is connected to at least one carbonnanotube structure, thereby forming an equipotential surface on thetransparent conductive layer 24. Specifically, the substrate 22 is aglass substrate. The electrodes 28 are strip-shaped and can be formed ofsilver, copper, or any alloy of at least one of such metals. Theelectrodes 28 are disposed directly on a surface of the transparentconductive layer 24 that faces away from the substrate 22. Theelectrodes 28 can be formed by one or more of spraying, electricaldeposition, and electroless deposition methods. Moreover, the electrodes28 can also be adhered to the surface of the transparent conductivelayer 24, e.g., by a silver-based slurry.

Further, in order to prolong operational life span and restrict couplingcapacitance of the touch panel 20, the transparent protective layer 26is disposed on the electrodes 28 and 29, and the transparent conductivelayer 24. The material of the transparent protective layer 26 can, e.g.,be selected from a group consisting of silicon nitride, silicon dioxide,benzocyclobutenes, polyester film, and polyethylene terephthalate. Thetransparent protective layer 26 can be a slick plastic film and receivea surface hardening treatment to protect the electrodes 28 and thetransparent conductive layer 24 from being scratched when in use.

In the present embodiment, the transparent protective layer 26 issilicon dioxide. The hardness and thickness of the transparentprotective layer 26 are selected according to practical needs. Thetransparent protective layer 26 is adhered to the transparent conductivelayer 24, e.g., via an adhesive.

The touch panel 20 can further include a shielding layer 25 disposed onthe second surface 222 of the substrate 22. A material of the shieldinglayer 25 can be indium tin oxide, antimony tin oxide, carbon nanotubefilm, and/or another conductive material. In the present embodiment, theshielding layer 25 is a carbon nanotube film. The carbon nanotube filmincludes a plurality of carbon nanotubes, and the orientation of thecarbon nanotubes therein may be arbitrarily determined. In the presentembodiment, the carbon nanotubes in the carbon nanotube film of theshielding layer 25 are arranged along a same direction. The carbonnanotube film is connected to ground and acts as a shield, thus enablingthe touch panel 20 to operate without interference (e.g.,electromagnetic interference).

Referring to FIG. 6, a display device 100 includes the touch panel 20, adisplay element 30, a touch panel controller 40, a central processingunit (CPU) 50, and a display element controller 60. The touch panel 20is connected to the touch panel controller 40 by an external circuit.The touch panel 20 can be spaced from the display element 30 by anintervening gap 106, or installed directly on the display element 30.The touch panel controller 40, the CPU 50 and the display elementcontroller 60 are electrically connected. The CPU 50 is connected to thedisplay element controller 60 to control the display element 30.

The display element 30 can be, e.g., a liquid crystal display, fieldemission display, plasma display, electroluminescent display, vacuumfluorescent display, cathode ray tube, or another display device.

When the shielding layer 25 is disposed on the second surface 222 of thesubstrate 22, a passivation layer 104 is disposed on a surface of theshielding layer 25 that faces away from the substrate 22. The materialof the passivation layer 104 can, for example, be silicon nitride orsilicon dioxide. The passivation layer 104 can be spaced from thedisplay element 30 or directly installed on the display element 30. Whenthe passivation layer 104 is spaced from the display element 30,understandably, two or more spacers 108 can be used. Thereby, the gap106 is provided between the passivation layer 104 and the displayelement 30. The passivation layer 24 can protect the shielding layer 22from chemical or mechanical damage.

In operation, voltages are applied to the electrodes 28 respectively. Auser operates the display device 100 by pressing or touching thetransparent protective layer 26 of the touch panel 20 with a touch tool,such as a finger, or an electrical pen/stylus 70, while visuallyobserving the display element 20 through the touch panel 20. In theillustration, the touch tool is the user's finger 70. Due to anelectrical field of the user, a coupling capacitance forms between theuser and the transparent conductive layer 24. For high frequencyelectrical current, the coupling capacitance is a conductor, and thusthe touch tool 70 takes away a little current from the touch point.Currents flowing through the electrodes 28 cooperatively replace thecurrent lost at the touch point. The quantity of current supplied byeach of electrodes 28 is directly proportional to the distances from thetouch point to the electrodes 28. The touch panel controller 40 is usedto calculate the proportion of the four supplied currents, and combinedwith the detailed directions of the carbon nanotube structures, therebydetecting coordinates of the touch point on the touch panel 20. Then,the touch panel controller 40 sends the coordinates of the touch pointto the CPU 50. The CPU 50 receives and processed the coordinates into acommand. Finally, the CPU 50 sends out the command to the displayelement controller 60. The display element controller 60 controls thedisplay of the display element 30 accordingly.

The properties of the carbon nanotubes provide superior toughness, highmechanical strength, and uniform conductivity to the carbon nanotubefilms of the carbon nanotube structures. Thus, the touch panel and thedisplay device adopting the carbon nanotube structures as the conductivelayer are durable and highly conductive. Furthermore, since the carbonnanotubes have excellent electrical conductivity properties, thetransparent conductive layer formed by a plurality of spaced carbonnanotube structures parallel to each other has a uniform resistancedistribution and optical transparent property, thus the touch panel andthe display device adopting the carbon nanotube structures have animproved sensitivity and accuracy. What is more, since each electrode isconnected with at least one end of at least one carbon nanotubestructure, it will confirm the position of the touching point bydetecting the voltage changes between two opposite electrodes moreaccurately, thereby it will improve the accuracy of the touch panel andthe display device using the same.

Finally, it is to be understood that the above-described embodiments areintended to illustrate rather than limit the invention. Variations maybe made to the embodiments without departing from the spirit of theinvention as claimed. The above-described embodiments illustrate thescope of the invention but do not restrict the scope of the invention.

1. A touch panel comprising: a substrate comprising a surface; a transparent conductive layer located on the surface, the transparent conductive layer comprising a plurality of first strip-shaped carbon nanotube structures spaced from each other and a plurality of second strip-shaped carbon nanotube structures crossing with the plurality of first strip-shaped carbon nanotube structures; two first electrodes opposite to and spaced from each other, the plurality of first strip-shaped carbon nanotube structures are in contact with and electrically connected to the two first electrodes at two opposite ends of each of the plurality of first strip-shaped carbon nanotube structures; and two second electrodes opposite to and spaced from each other, wherein the plurality of second strip-shaped carbon nanotube structures are in contact with and electrically connected to the two second electrodes at two opposite ends of each of the plurality of first strip-shaped carbon nanotube structures.
 2. The touch panel as claimed in claim 1, wherein the plurality of first strip-shaped carbon nanotube structures arc parallel to each other, and the plurality of second strip-shaped carbon nanotube structures are parallel to each other.
 3. The touch panel as claimed in claim 2, wherein each of the plurality of first strip-shaped carbon nanotube structures and the plurality of second strip-shaped carbon nanotube structures comprises a plurality of carbon nanotubes, the plurality of carbon nanotubes of each of the plurality of first strip-shaped carbon nanotube structures are arranged along a same direction from one of the two first electrodes to the other of the two first electrodes, the plurality of carbon nanotubes of each of the plurality of second strip-shaped carbon nanotube structures are arranged along a same direction from one of the two second electrodes to the other of the two second electrodes.
 4. The touch panel as claimed in claim 3, wherein the plurality of carbon nanotubes of each of the plurality of first strip-shaped carbon nanotube structures are arranged along the same direction from one of the two first electrodes to the other of the two first electrodes, and the plurality of carbon nanotubes of each of the plurality of second strip-shaped carbon nanotube structures are arranged along the same direction from one of the two second electrodes to the other of the two second electrodes.
 5. The touch panel as claimed in claim 1, wherein each of the plurality of first strip-shaped carbon nanotube structures and the plurality of second strip-shaped carbon nanotube structures comprises at least one carbon nanotube film, the at least one carbon nanotube film comprising a plurality of carbon nanotubes arranged along a same direction.
 6. The touch panel as claimed in claim 5, wherein the plurality of carbon nanotubes of the at least one carbon nanotube film comprises a plurality of successively oriented carbon nanotube segments joined end to end by van der Waals attractive force therebetween.
 7. The touch panel as claimed in claim 1, wherein each of the plurality of first strip-shaped carbon nanotube structures and the plurality of second strip-shaped carbon nanotube structures comprises a plurality of carbon nanotube films stacked with each other, and adjacent carbon nanotube films are combined by van der Waals attractive force therebetween.
 8. The touch panel as claimed in claim 1, wherein a thickness of each of the plurality of first strip-shaped carbon nanotube structures and the plurality of second strip-shaped carbon nanotube structures ranges from about 0.5 nanometers to about 100 micrometers.
 9. The touch panel as claimed in claim 1, wherein a distance between adjacent first strip-shaped carbon nanotube structures of the plurality of first strip-shaped carbon nanotube structures ranges from about 5 nanometers to about 1 millimeter, and a distance between adjacent second strip-shaped carbon nanotube structures of the plurality of second strip-shaped carbon nanotube structures ranges from about 5 nanometers to about 1 millimeter.
 10. The touch panel as claimed in claim 1, wherein each of the two first electrodes and the two second electrodes comprises metal.
 11. The touch panel as claimed in claim 1, further comprising a transparent protective layer disposed on the transparent conductive layer, the transparent protective layer comprises a material that is selected from the group consisting of silicon nitrides, silicon dioxides, benzocyclobutenes, polyester films, and polyethylene terephthalates.
 12. The touch panel as claimed in claim 1, further comprising a shielding layer disposed on the second surface of the substrate, and a material of the shielding layer is selected from the group consisting of indium tin oxides, antimony tin oxides, and carbon nanotube films.
 13. The display device as claimed in claim 1, wherein the plurality of second strip-shaped carbon nanotube structures are perpendicular to the plurality of first strip-shaped carbon nanotube structures. 